Clear PVC cleaner, Clear PVC cement.
Sketch out what you want, basic layout, how many valves and so forth. Plan for the future possibilities.
Measure once, twice, three times the charm.
Make a dry fit mock up of the plumbing and see if it fits. Adjust plan as necessary.
My first effort was my current tank. It took me 2 tries to get what I wanted.
I ended up with 3 gate valves 1/2 x 1/2 inch slip fit.
I used reducing Ts 3/4 x 3/4 x 1/2.
I used clear silicone tubing from the pump to the manifold.
I put a true union ball valve last so I could shut off back flow and remove the whole thing if needed.
Finished effort was this:
I'm still working on the refugium parts, so one gate valve will be used for that.
The other 2 are for Spyglass reactors, but I don't need to run them right now.
There's a million ways to do this.
Search the intarwebs and you'll get lots of ideas.
